The invention relates to ventilating or equalizing the pressure between the middle ear and the outer ear. More particularly, the invention relates to an oval shaped ear tube to provide improved drainage and ventilation from the middle ear to the outer ear.
Recurrent ear infections, particularly among young children, may lead to long term hearing loss or permanent retraction of the tympanic membrane or eardrum. The treatment for patients with chronic ear infections is generally to insert ventilation tubes into the tympanic membrane or eardrum to allow ventilation and drainage into the outer ear from the middle ear. By providing a ventilation or drainage path from the middle ear to the outer ear, pressure or fluid does not build up within the middle ear which can cause pain and hearing loss. Ear tubes are generally made of materials such as stainless steel, Teflon, Silastic, nylon or other similar types of materials. There is generally an inner flange on the ear tube to prevent the tube from being readily pushed out by infection or other fluid pressure building up in the middle ear region behind the ear drum. As recognized in U.S. Pat. No. 4,775,370 ('370 patent), known ear tube designs generally have a lumen of constant or uniform diameter. The '370 patent describes a technique for utilizing an ear tube that has an inner hollow circular cross section that increases along the length of the tube from the inner end to the outer end of the tube.
The current ear tube styles have several disadvantages. First, when the tubes extrude, a permanent hole or perforation may be left in the ear drum which requires surgical repair. The surgical repair is generally not performed until after an extended period of time to ensure that the child has outgrown whatever problems were causing the chronic ear infections. However, because the surgical repair may not occur for several years and water must be kept out of the ear until the perforation is repaired, the perforation may inconvenience the patient and interfere with water activities such as swimnming. The current uniform round shape of the ear tubes that are presently being used may also contribute to the formation of ear tube perforations.
Second, ear tubes often extrude too soon, or before the child has outgrown the age of ear infections. The highest incidence of ear infections generally occurs in children less than four or five years of age. Thus, tubes placed in young children less then three years of age ideally should stay in place for two or more years to allow the child to outgrow the age when ear infections are most likely to occur. Maintaining the ear tubes in place for two or more years helps avoid exposing the child to a second surgical procedure to replace the extruded ear tubes which entails the concurrent dangers of a general anesthetic. Currently, the incidence of repeat placement of ear tubes is greater than thirty percent.
Ear tubes are generally held in place by a round flange at the bottom of the tube. The round flange typically holds the tube in place for four to twelve months. Other known techniques have used a pointed flange which protrudes from the bottom of the tube. This technique typically maintains the tube in place for approximately nine to eighteen months. Another technique is to use a long, straight flange protruding from the bottom of the tube. This technique is designed to hold the tube in place permanently. Although in practice, the length of time the tube stays in place varies and averages approximately three years.
Third, ear tubes can become blocked by ear wax (cerumen) or fluid from the middle ear that has dried in the lumen of the tube. If the tube is blocked, its ability to ventilate and drain the middle ear cavity is eliminated. Most ear tubes have a relatively small round shaped lumen that is easily blocked. A blocked ear tube becomes a problem when the next ear infection occurs and the pressure builds up in the middle ear behind the eardrum. The pressure may not only wash out the puss developing in the ear, but it can also dislodge the plugged tube itself and perforate the ear drum causing extreme pain and requiring surgical repair. If surgical repair is required, then the patient will again be exposed to a general anesthetic with its own concurrent dangers.
A fourth problem with current ear tube designs is that it is difficult to examine the lumen of the tube when the tubes are in place. The difficulty in viewing the lumen is caused by the angle of the ear drum relative to the ear canal. Due to the angle of the ear drum, once the ear tube is in place it is difficult to examine the lumen and identify whether the tube is blocked by ear wax (cerumen) or dried fluid. Identifying the ear tube's source of blockage aids in determining the appropriate treatment to unblock the ear tube and ensure proper ventilation from the middle ear to the outer ear.
There is no known ear tube device which allows easy examination while implanted in the eardrum that significantly reduces the risks of extruding to soon, perforating the tympanic membrane, or blocking the ventilation path.